The researchers selected a fast-growing marine bacterium, Vibrio natriegens, which has exceptional tolerance for high salt concentration and a capacity for utilizing various carbon sources. They introduced an aerobic sulfate reduction pathway into V. natriegens and trained the engineered strain to utilize different metal and carbon sources in order to produce semiconductor biohybrids directly from such wastewater. 

Their primary target chemical for production was 2,3-butanediol (BDO), a valuable commodity chemical. 

By engineering a strain of V. natriegens, they generated hydrogen sulfide, which played a pivotal role in facilitating the production of CdS nanoparticles that efficiently absorb light. These nanoparticles, renowned for their biocompatibility, enabled the in-situ creation of semiconductor biohybrids and enabled the non-photosynthetic bacteria to utilize light. 

The results showed that these sunlight-activated biohybrids exhibited significantly enhanced BDO production, surpassing yields achievable through bacterial cells alone. Furthermore, the process displayed scalability, achieving solar-driven BDO production on a substantial 5-liter scale using actual wastewater. 

“The biohybrid platform not only boasts a lower carbon footprint but also reduces product costs, leading to an overall smaller environmental impact when compared to both traditional bacterial fermentation and fossil fuel-based BDO production methods,” said Prof. GAO. “Remarkably, these biohybrids could be produced using a variety of wastewater sources.”